Although the Philippines is one of the few countries in Asia to be spared the devastating effects of the AIDS virus at the present time, there is still cause for concern due to the worldwide, rapid, and uncontrolled spread of AIDS. Longitudinal determinants of STD/HIV prevention behaviors among commercial sex workers (CSWs) in the Philippines have not taken place. We propose a joint effort by faculty from the University of the Philippines, Regional Health Officers from the Philippines, and faculty from UCLA to assess the psychosocial and environmental determinants and practices of CSWs and manager/owners of the establishments in which they are employed. We proposed to test a conceptual/theoretical psychosocial, community organization model comprising endogenous and exogenous factors hypothesized to directly influence HIV prevention behaviors. The educational program, based on this theroretical factors targeted to the CSWs (communication skills, empowerment, self-efficacy and self-esteem) and the managers/owner of the establishments. A four-group quasi- experimental design will contrast 1) the effects of peer educational counseling alone, 2) managerial training/educational policy, 3) combined peer counseling plus managerial training, and 4) a standard care (control) group. A total of 2,000 CSWs will be selected from over 250 establishments in four areas of the Southern Philippines. Bivariate and multivariate statistical procedures, including structural equation modeling, will be used to evaluate causal hypotheses. The research is highly relevant, urgent, and timely; results will be directly applied to the National AIDS Prevention and Control Program.